Effect of Elastic Properties of the Fluids on the Particle Settling Velocity

2017 ◽  
Author(s):  
Sumanth Kumar Arnipally ◽  
Ergun Kuru
Keyword(s):  
Elastic Properties ◽  
Shear Viscosity ◽  
Settling Velocity ◽  
Relaxation Times ◽  
Average Diameter ◽  
Spherical Particles ◽  
Molecular Weights ◽  
Elastic Fluids ◽  
The Impact ◽  
Elastic Characteristics

An experimental study was performed to investigate the influence of fluid elastic properties on the settling velocity of spherical particles in viscoelastic polymer fluids. The Particle Image Shadowgraph (PIS) technique was used to measure the settling velocity of the spherical particles (with average diameter of 2mm) in the hydrolyzed poly acrylamide (HPAM) polymer test fluids. Test fluids were prepared by mixing 3 different grades of HPAM (with molecular weights of; 500,000; 8,000,000; and 20,000,000) at polymer concentrations of 0.09 and 0.1% by weight. Shear viscosity and oscillatory measurements were carried out to characterize the test fluids. The test fluids were formulated in such a way that they had almost identical shear viscosity characteristics while showing significantly different elastic properties. The relaxation time was used to quantify the elastic characteristics of the fluids. To quantify the impact of elasticity, the experimentally measured settling velocities were compared to the values calculated by using the model developed for predicting settling velocity of spherical particles in power law (visco-inelastic) fluids [1]. Experimental results indicated that the settling velocity of spherical particles in visco-elastic fluids decreased significantly with the increasing elasticity (measured in terms of relaxation times) of the fluids.

Settling Velocity of Particles in Viscoelastic Fluids: A Comparison of the Shear-Viscosity and Elasticity Effects

SPE Journal ◽  
2018 ◽  
Vol 23 (05) ◽  
pp. 1689-1705 ◽  
Author(s):  
Sumanth Kumar Arnipally ◽  
Ergun Kuru
Keyword(s):  
Elastic Properties ◽  
Shear Viscosity ◽  
Settling Velocity ◽  
Particle Diameter ◽  
Viscoelastic Fluids ◽  
Spherical Particles ◽  
High Shear ◽  
Fluid Shear ◽  
Particle Settling ◽  
Fluid Elasticity

Summary The objective of this paper is to determine how fluid shear viscosity and elasticity might influence the particle-settling velocity, and even more so to answer the question of which one of these two rheological properties is more dominant in controlling the particle-settling velocity when viscoelastic drilling fluids are used. The settling velocities of spherical particles (diameters: 1.18, 1.5, 2, and 3 mm) in partially hydrolyzed polyacrylamide (HPAM) polymer fluids were measured using the particle-image-shadow graph (PIS) technique. Two sets of test fluids were formulated by mixing three different grades of HPAM (molecular weights of 500,000, 8 million, and 20 million g/g mol) at polymer concentrations of 0.09, 0.05, and 0.03 wt%. The shear-viscosity and elasticity characteristics of test fluids were determined by performing shear-viscosity and frequency-sweep oscillatory measurements, respectively. The first set of fluids had almost identical shear-viscosity characteristics while showing significantly different elastic properties (quantified in terms of relaxation time). The second set of fluids had similar elastic properties but different shear-viscosity characteristics. In addition, the effect of the particle size on the settling velocities in these test fluids was also investigated. The experimentally measured settling velocities were compared with the values calculated from the Shah et al. (2007) model developed for predicting the settling velocity of spherical particles in power-law (viscoinelastic) fluids as well as the values calculated from the Malhotra and Sharma (2012) correlation developed for settling velocity in shear-thinning viscoelastic fluids in unconfined media. Experimental results showed the following: When the fluids with similar shear-viscosity profiles were used, the settling velocity of spherical particles decreased significantly with the increasing fluid elasticity. The settling-velocity values can be 14 to 50 times overestimated if the effect of the elasticity is not considered. At constant elasticity, the settling velocity of spherical particles also decreased significantly when the fluid shear viscosity was increased. The spherical particle-settling velocity increased pronouncedly as particle diameter increased from 1.18 to 3 mm. However, the magnitude of the increase in settling velocity with the increasing particle diameter is less for the samples with higher elasticity and similar shear-viscosity characteristics. The fluid shear viscosity and the elasticity both seem to have significant effect on the particle-settling velocity. However, from the field operational point of view, fluids with high shear-viscosity values are not always practical to use because the high shear viscosity increases parasitic pressure losses and potentially has a negative effect on the drilling rate. Hence, in such cases increasing the fluid elasticity can help to reduce the particle-settling velocity even at lower shear-viscosity values. By conducting experiments under controlled conditions, we were able to quantify the individual effects of fluid shear viscosity and elasticity on the particle-settling velocity for the first time in drilling literature.

Saltation and incipient suspension above a flat particle bed below a turbulent boundary layer

2000 ◽  
Vol 417 ◽  
pp. 77-102 ◽  
Author(s):  
K. NISHIMURA ◽  
J. C. R. HUNT
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Settling Velocity ◽  
Particle Density ◽  
Surface Wind ◽  
Spherical Particles ◽  
Flux Profile ◽  
Horizontal Flux ◽  
The Mean ◽  
The Impact

Experiments were conducted in a wind tunnel in which a turbulent boundary layer was naturally grown over flat beds of three types of nearly mono-disperse spherical particles with different diameters, densities and coefficient of restitution (r) (snow, 0.48 mm, 910 kg m−3; mustard seeds, 1.82 mm, 1670 kg m−3, r = 0.7; ice particles, 2.80 mm, 910 kg m−3, r = 0.8–0.9). The surface wind speeds (defined by the friction velocity u∗) were varied between 1.0 and 1.9 times the threshold surface wind speed (defined by u∗t). The trajectories, and ejection and impact velocities of the particles were recorded and analysed, even those that were raised only about one diameter into the flow.Measurements of the average horizontal flux of saltating particles per unit area, f(z), at each level z above the surface showed that, for u∗/u∗t [les ] 1.5, f(z) is approximately independent of the particle density and decreases exponentially over a vertical scale length lf, that is about 3 to 4 times the estimated mean height of the particle trajectories 〈h〉. Numerical simulations of saltating grains were computed using the measured probabilities of ejection velocities and the mean velocity profile of the air flow, but neglecting the direct effect of the turbulence. The calculated mean values of the impact velocities and the trajectory dimensions were found to agree with the measurements in the saltation range, where u∗/u∗t < 1.5. Similarly, in this range the simulations of the horizontal flux profile and integral are also consistent with the measurements and with Bagnold's u∗3 formula, respectively.When u∗/u∗t [ges ] 1.5, and u∗/VT [ges ] 1/10, where VT is the settling velocity, a transition from saltation to suspension occurs. This is indicated by the change in the mean mass flux profile which effectively becomes uniform with height (z) up to the top of the boundary layer. An explanation is provided for this low value of turbulence at transition relative to the settling velocity in terms of the random motion of the particles under the action of the turbulence when they reach the tops of their parabolic trajectories. The experiments show that, as u∗/u∗t increases from 1.0 to 1.9 the normalized mean vertical impact velocity 〈V3I〉/u∗ decreases by nearly 60% to about 0.6, which is less than 50% of the value for fluid particles. There is also a decrease in the vertical and horizontal component of the ejection velocity to values of 0.8 and 2.3, which are much less than their values in the saltation regime. We hypothesize that at the transition from saltation to suspension the ejection process changes quite sharply from being determined by impact collisions to being the result of aerodynamic lift forces and upward eddy motions.

scholarly journals Non-Isothermal Decomposition as Efficient and Simple Synthesis Method of NiO/C Nanoparticles for Asymmetric Supercapacitors

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 187
Author(s):  
Daria Chernysheva ◽  
Ludmila Pudova ◽  
Yuri Popov ◽  
Nina Smirnova ◽  
Olga Maslova ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Synthesis Method ◽  
Average Diameter ◽  
Carbon Support ◽  
Spherical Particles ◽  
Support Surface ◽  
Isothermal Decomposition ◽  
Step Method ◽  
Nickel Oxide Nanoparticles ◽  
Electrode Cell

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min).

scholarly journals Exosome Traceability and Cell Source Dependence on Composition and Cell-Cell Cross Talk

2021 ◽  
Vol 22 (10) ◽  
pp. 5346
Author(s):  
Rabab N. Hamzah ◽  
Karrer M. Alghazali ◽  
Alexandru S. Biris ◽  
Robert J. Griffin
Keyword(s):  
Donor Cell ◽  
Average Diameter ◽  
Cell Types ◽  
Cell Interaction ◽  
Target Cells ◽  
Remote Communication ◽  
Normal Cells ◽  
Growth Environment ◽  
Cell Components ◽  
The Impact

Exosomes are small vesicles with an average diameter of 100 nm that are produced by many, if not all, cell types. Exosome cargo includes lipids, proteins, and nucleic acids arranged specifically in the endosomes of donor cells. Exosomes can transfer the donor cell components to target cells and can affect cell signaling, proliferation, and differentiation. Important new information about exosomes’ remote communication with other cells is rapidly being accumulated. Recent data indicates that the results of this communication depend on the donor cell type and the environment of the host cell. In the field of cancer research, major questions remain, such as whether tumor cell exosomes are equally taken up by cancer cells and normal cells and whether exosomes secreted by normal cells are specifically taken up by other normal cells or also tumor cells. Furthermore, we do not know how exosome uptake is made selective, how we can trace exosome uptake selectivity, or what the most appropriate methods are to study exosome uptake and selectivity. This review will explain the effect of exosome source and the impact of the donor cell growth environment on tumor and normal cell interaction and communication. The review will also summarize the methods that have been used to label and trace exosomes to date.

scholarly journals Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 519
Author(s):  
Vitalii Bezgin ◽  
Agata Dudek ◽  
Adam Gnatowski
Keyword(s):  
Mechanical Properties ◽  
Scientific Paper ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Wide Range ◽  
Strength Tests ◽  
Materials Used ◽  
Styrene Butadiene ◽  
The Impact

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.

scholarly journals Air mediates the impact of a compliant hemisphere on a rigid smooth surface

Soft Matter ◽  
2021 ◽  
Author(s):  
Siqi Zheng ◽  
Sam Dillavou ◽  
John M. Kolinski
Keyword(s):  
Elastic Body ◽  
Elastic Properties ◽  
Impact Velocity ◽  
Solid Surface ◽  
High Speed ◽  
Smooth Surface ◽  
High Speed Imaging ◽  
The Impact ◽  
Rigid Smooth

When a soft elastic body impacts upon a smooth solid surface, the intervening air fails to drain, deforming the impactor. High-speed imaging with the VFT reveal rich dynamics and sensitivity to the impactor's elastic properties and the impact velocity.

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

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